Living organisms with damaged blood vessels avoid hemorrhage death by rapid production of thrombin. However, excess production of thrombin due to inflammatory reaction in damaged blood vessels causes thrombosis, which impairs the function of essential organs. Thrombin inhibitors such as heparin and warfarin, which inhibit thrombin production or directly block thrombin activity, have long been used as anticoagulants to treat or prevent thrombosis.
Still, it cannot be said that such medicaments are very satisfactory from a medical standpoint, and efforts continue throughout the world toward research and development of new orally administrable anticoagulants with excellent dose response and low risk of bleeding.
The blood clotting mechanism has been classified into two pathways, the “intrinsic clotting pathway” which begins with activation of factor XII (FXII) upon contact with negative charged substances, and the “extrinsic clotting pathway” which is activated by tissue factor (TF) and factor VII (FVII). Since the pathology of thrombosis onset is associated with specific expression of TF, it has been suggested that extrinsic clotting is of major importance. Compounds that inhibit clotting factor VIIa, which is furthest upstream in the extrinsic clotting pathway of the clotting cascade, are thought to have potential use as therapeutic and/or prophylactic agents for diseases associated with thrombus formation, such as thrombosis, in which the extrinsic clotting mechanism plays a part.
As compounds that inhibit clotting factor VIIa there are known in the prior art amidinonaphthol derivatives (see Non-patent document 1), amidino derivatives (see Patent document 1), N-sulfonyl dipeptide derivatives (see Patent document 2), 6-[[(allyl)oxy]methyl]naphthalene-2-carboxylmidamide derivatives (see Patent document 3) and phenylglycine derivatives (Patent documents 4 and 5).
However, these known compounds are inadequate from the standpoint of inhibition activity against clotting factor VIIa, blood clotting effects and thrombosis-treating effects.    [Non-patent document 1] Tetrahedron, 55, p. 6219, 1999    [Patent document 1] EP 1078917    [Patent document 2] WO 00/58346    [Patent document 3] WO 00/66545    [Patent document 4] WO 00/35858    [Patent document 5] WO 00/41531